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ABB semaphore protection overhaul The ABB semaphone protection logic that came with TCS211 from TI was broken in several ways: * Some semaphore-protected functions were called from Application_Initialize() context. NU_Obtain_Semaphore() called with NU_SUSPEND fails with NU_INVALID_SUSPEND in this context, but the return value wasn't checked, and NU_Release_Semaphore() would be called unconditionally at the end. The latter call would increment the semaphore count past 1, making the semaphore no longer binary and thus no longer effective for resource protection. The fix is to check the return value from NU_Obtain_Semaphore() and skip the NU_Release_Semaphore() call if the semaphore wasn't properly obtained. * Some SPI hardware manipulation was being done before entering the semaphore- protected critical section. The fix is to reorder the code: first obtain the semaphore, then do everything else. * In the corner case of L1/DSP recovery, l1_abb_power_on() would call some non-semaphore-protected ABB & SPI init functions. The fix is to skip those calls in the case of recovery. * A few additional corner cases existed, all of which are fixed by making ABB semaphore protection 100% consistent for all ABB functions and code paths. There is still one remaining problem of priority inversion: suppose a low- priority task calls an ABB function, and some medium-priority task just happens to preempt right in the middle of that semaphore-protected ABB operation. Then the high-priority SPI task is locked out for a non-deterministic time until that medium-priority task finishes its work and goes back to sleep. This priority inversion problem remains outstanding for now.
author Mychaela Falconia <falcon@freecalypso.org>
date Mon, 26 Apr 2021 20:55:25 +0000
parents fa8dc04885d8
children
line wrap: on
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/*
+-----------------------------------------------------------------------------
|  File     : gdd_dio_queue.h
+-----------------------------------------------------------------------------
|  Copyright 2002 Texas Instruments Berlin, AG
|                 All rights reserved.
|
|                 This file is confidential and a trade secret of Texas
|                 Instruments Berlin, AG
|                 The receipt of or possession of this file does not convey
|                 any rights to reproduce or disclose its contents or to
|                 manufacture, use, or sell anything it may describe, in
|                 whole, or in part, without the specific written consent of
|                 Texas Instruments Berlin, AG.
+-----------------------------------------------------------------------------
|  Purpose  : Definitions for gdd_dio_queue.c
+-----------------------------------------------------------------------------
*/

#ifndef GDD_DIO_QUEUE_H
#define GDD_DIO_QUEUE_H

/*==== INCLUDES =============================================================*/

#include "gdd.h"

#include "p_dio.h"


/*==== DEFINITIONS ==========================================================*/

/**
 * Maximum numbers of simultaneous DIO buffers provided by PSI.
 * Might be increased at one stage in the future.
 */
#define GDD_MAX_DIO_BUF   2

/**
 * Definition of buffer queue
 */
typedef struct
{
  T_dio_buffer * elems[GDD_MAX_DIO_BUF];
  U16 next_in;
  U16 next_out;  
} T_GDD_BUF_QUEUE;


/*==== EXPORTS ===============================================================*/

/*
+------------------------------------------------------------------------------
| Function    : gdd_dio_queue_clear
+------------------------------------------------------------------------------
| Description : Clear a queue
|
| Parameters  : queue            - pointer to queue to be cleared
|
+------------------------------------------------------------------------------
*/
EXTERN void gdd_dio_queue_clear(T_GDD_BUF_QUEUE *queue);


/*
+------------------------------------------------------------------------------
| Function    : gdd_dio_queue_is_empty
+------------------------------------------------------------------------------
| Description : Check if a queue is empty
|
| Parameters  : queue            - pointer to queue to be checked
|
| Return      : TRUE if queue is empty, FALSE otherwise
+------------------------------------------------------------------------------
*/
EXTERN BOOL gdd_dio_queue_is_empty(const T_GDD_BUF_QUEUE *queue);


/*
+------------------------------------------------------------------------------
| Function    : gdd_dio_queue_is_full
+------------------------------------------------------------------------------
| Description : Check if a queue is full
|
| Parameters  : queue            - pointer to queue to be checked
|
| Return      : TRUE if queue is full, FALSE otherwise
+------------------------------------------------------------------------------
*/
EXTERN BOOL gdd_dio_queue_is_full(const T_GDD_BUF_QUEUE *queue);


/*
+------------------------------------------------------------------------------
| Function    : gdd_dio_enqueue
+------------------------------------------------------------------------------
| Description : Enqueue an item into the queue
|
| Parameters  : elem             - item to be enqueued
|               queue            - pointer to queue to be modified
|               pos              - to return the position of the enqueued item
|
| Return      : TRUE if item is enqueued, FALSE if the queue is already full
+------------------------------------------------------------------------------
*/
EXTERN BOOL gdd_dio_enqueue(T_dio_buffer *elem, T_GDD_BUF_QUEUE *queue, /*out*/U16 *pos);


/*
+------------------------------------------------------------------------------
| Function    : gdd_dio_dequeue
+------------------------------------------------------------------------------
| Description : Dequeue an item into the queue
|
| Parameters  : queue            - pointer to queue to be modified
|               elem             - to return the dequeued item
|
| Return      : TRUE if item is dequeued, FALSE if the queue is empty
+------------------------------------------------------------------------------
*/
EXTERN BOOL gdd_dio_dequeue(T_GDD_BUF_QUEUE *queue, /*out*/T_dio_buffer **elem);

/*
+------------------------------------------------------------------------------
| Function    : gdd_dio_queue_peek_next_for_dequeue
+------------------------------------------------------------------------------
| Description : Retrieves the element that is next to dequeue without actually
|               dequeuing it.
|
| Parameters  : queue            - pointer to queue
|               pos              - position of element
|               elem             - to output element value
|
| Return      : TRUE if item is available, FALSE if the queue is empty
+------------------------------------------------------------------------------
*/
EXTERN BOOL gdd_dio_queue_peek_next_for_dequeue
(const T_GDD_BUF_QUEUE *queue, T_dio_buffer **elem);

/*
+------------------------------------------------------------------------------
| Function    : gdd_dio_queue_peek
+------------------------------------------------------------------------------
| Description : Retrieve element at specified position
|
| Parameters  : queue            - pointer to queue
|               pos              - position of element
|               elem             - to output element value
|
| Attention   : This function does not do bounds checking
+------------------------------------------------------------------------------
*/
EXTERN void gdd_dio_queue_peek(const T_GDD_BUF_QUEUE *queue, U16 pos, /*out*/T_dio_buffer **elem);

#endif /* !GDD_DIO_QUEUE_H */